<!DOCTYPE html>

  <meta charset="UTF-8">

  <title>CSS Values and Units Test: computed value of 'z-index' when specified with calc() function and fractional values</title>

  <link rel="author" title="Gérard Talbot" href="http://www.gtalbot.org/BrowserBugsSection/css21testsuite/">
  <link rel="help" href="https://www.w3.org/TR/css-values-4/#calc-range">

  <meta content="This test verifies how 2 calc() functions are computed for 'z-index' when involved expressions end up being numbers halfway between adjacent integers." name="assert">

  <script src="../../resources/testharness.js"></script>

  <script src="../../resources/testharnessreport.js"></script>

  <div id="target"></div>

  <script>
  function startTesting()
  {

  var targetElement = document.getElementById("target");

    function verifyComputedStyle(property_name, initial_value, specified_value, expected_value)
    {

    test(function()
      {

      targetElement.style.setProperty(property_name, initial_value);

      /*
      The purpose of the initial_value is to act as a fallback
      value in case the calc() function in the specified value
      fails or in case it generates an invalid value. Since we
      are running 2 consecutive tests on the same element,
      then it is necessary to reset its property to an initial
      value.
      */

      targetElement.style.setProperty(property_name, specified_value);

      assert_equals(getComputedStyle(targetElement)[property_name], expected_value);

      }, `testing ${property_name}: ${specified_value}`);
    }

 /* verifyComputedStyle(property_name, initial_value, specified_value, expected_value) */
    verifyComputedStyle("z-index", "auto", "calc(2.5 / 2)", "1");
    verifyComputedStyle("z-index", "auto", "calc(3 / 2)", "2");
    verifyComputedStyle("z-index", "auto", "calc(3.5 / 2)", "2");
    verifyComputedStyle("z-index", "auto", "calc(-2.5 / 2)", "-1");
    verifyComputedStyle("z-index", "auto", "calc(-3 / 2)", "-1");
    verifyComputedStyle("z-index", "auto", "calc(-3.5 / 2)", "-2");
  }

  startTesting();

  </script>
